Idiopathic spinal cord herniation with duplicated dura mater and dorsal subarachnoid septum. Report of a case and review of the literature.

Yamamoto N, Katoh S, Higashino K, Sairyo K - Int J Spine Surg (2014)

Bottom Line:
Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy.The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated.After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced.

Affiliation: Department of Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.

ABSTRACT

Background: Idiopathic spinal cord herniation (ISCH) is a rare condition and its pathogenesis remains unclear. The purpose of this case report is to present an ISCH case with dorsal subarachnoid septum suggesting the pathogenesis of ISCH being adhesions from preexisting inflammation.

Methods: Single case report.

Results: A 60-year-old woman presented with Brown-Séquard syndrome below the level of T6. Magnetic resonance imaging revealed the thoracic spinal cord was displaced ventrally, and the dorsal subarachnoid space was enlarged and had a septum between the spinal cord and dura mater. Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy. The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated. After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced.

Conclusions: The present case indicates that adhesions around the dura mater can be the pathogenesis of ISCH.

Mentions:
MRI showed the thoracic spinal cord displaced ventrally to the right, an enlarged dorsal subarachnoid space, and a midline septum between the dura mater and spinal cord at T5–T6 disc level (Figure 1). The midline septum separated dorsal subarachnoid space at the level, but not cranial nor caudal levels. Spinal cord was flattened, and high T2 signal intensity was not detected. Ventral spinal cord deviation was limited at T5–T6 disc level. Scalloping of the vertebral body4 and erosion of the dura mater by a herniated and calcified disc5 were not seen. CT myelography showed the compressed spinal cord ventrally as well as no pooling and extravasation of contrast medium ventral to the spinal cord. As for dorsal side of spinal cord, it also showed an uninterrupted flow of contrast material and no filling defect (Figure 2). A nuclear trail sign, a feature suggestive of a path of herniation of the nucleus pulposus, was not present. The septum seen on MRI could not be distinguished with contrast medium on CT myelography.

Mentions:
MRI showed the thoracic spinal cord displaced ventrally to the right, an enlarged dorsal subarachnoid space, and a midline septum between the dura mater and spinal cord at T5–T6 disc level (Figure 1). The midline septum separated dorsal subarachnoid space at the level, but not cranial nor caudal levels. Spinal cord was flattened, and high T2 signal intensity was not detected. Ventral spinal cord deviation was limited at T5–T6 disc level. Scalloping of the vertebral body4 and erosion of the dura mater by a herniated and calcified disc5 were not seen. CT myelography showed the compressed spinal cord ventrally as well as no pooling and extravasation of contrast medium ventral to the spinal cord. As for dorsal side of spinal cord, it also showed an uninterrupted flow of contrast material and no filling defect (Figure 2). A nuclear trail sign, a feature suggestive of a path of herniation of the nucleus pulposus, was not present. The septum seen on MRI could not be distinguished with contrast medium on CT myelography.

Bottom Line:
Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy.The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated.After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced.

Affiliation:
Department of Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.

ABSTRACT

Background: Idiopathic spinal cord herniation (ISCH) is a rare condition and its pathogenesis remains unclear. The purpose of this case report is to present an ISCH case with dorsal subarachnoid septum suggesting the pathogenesis of ISCH being adhesions from preexisting inflammation.

Methods: Single case report.

Results: A 60-year-old woman presented with Brown-Séquard syndrome below the level of T6. Magnetic resonance imaging revealed the thoracic spinal cord was displaced ventrally, and the dorsal subarachnoid space was enlarged and had a septum between the spinal cord and dura mater. Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy. The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated. After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced.

Conclusions: The present case indicates that adhesions around the dura mater can be the pathogenesis of ISCH.